Axially spreading friction clutch



United States Patent Raoul Joern Lindau;

Peter Reichardt, Fellbach, Germany [21] Appl. No. 793,340

[72] inventors [22] Filed Jan. 23,1969 [45] Patented Dec. 15, 1970 [73]Assignee .loern G.m.b.l l.

Oel'fingen, Germany a corporation of Germany [32] Priority Jan. 27, 1968[33] Germany [31] No. 1,675,152

[54] AXIALLY SPREADING FRICTION CLUTCH 10 Claims, 4 Drawing Figs.

52 u.s.c1 192/70,-

192/70.15;7o.1s;1oe.1 s11 1nt.Cl ..F16d13/26 {50] Field of Search192/70, 7015, 70.18, 106.1,66

[56] References Cited UNITED STATES PATENTS 939,663 11/1909 Cameron192/7015 2,502,798 4/1950 Nabstedt 192/70(X) 3,167,163 l/1965 Smirl eta1 192/7018 Primary Examiner-Allan D. Herrmann Atlorney- Karl F. RossABSTRACT: A silent clutch has a flange connectable to a drive shaft anda housing connectable to a driven shaft. Two axially displaceable androtatable clutch rings are rotationally fixed on the flange anddisplaceable away from same by pneumatic cylinders. On axialdisplacement the clutch rings frictionally engage the housing and couplethe two shafts rotationally together. The rings are connected to theflange by a plurality of elongated links laying one behind the other ina circular pattern each one with one end connected to the flange and oneto the ring via ball-and-socket joints. These joints have a layer ofrubber between the socket formed in the link end and the ball head whichlayer frictionally and resiliently yields upon separation of the clutchring from the flange and is thus stressed to return the ring to theflange in the off position ofthe clutch.

AXIALLY SPREADING FRICTION CLUTCH Our present invention relates to aclutch, in particular to a friction clutch for releasably' rotationallyconnecting two rotatable shafts together.

Clutches are known wherein a drive shaft carries a flange with aplurality of axially extending teeth or splines. A clutch ring is formedso as to be angularly or rotationally entrained by these teeth and isaxially shiftable relative to the flange by a lever, or a hydraulic orpneumatic cylinder.

Another flange is arranged axially in front of the clutch ring such thaton displacement of this latter the two come into frictional contact andconnect the first shaft with a driven shaft carrying this secondflange.A coil spring returns the clutch ring to its starting position. Severalrings and flanges can be provided, and'the clutch surfaces are usuallyfrustoconical for ideal braking action and automatic centering.

. This type of clutch has some notable disadvantages. First of all it isnoisy and operates roughly. The braking ring scrapes back and forth onthe teeth, and wears out the latter, while increasing play. Also thereturn spring often'becomes noisy.

Furthermore, this constant scraping causes the teeth to wear heavilywhich brings about even more .noise as a result of the undesirable playin the clutch. Finally the return spring takes up quite a bit ofspace.

One of the objects of our present invention is therefore to provide aclutch which overcomes these disadvantages.

Another object is to provide a reasonably silent and smoothoperatingclutch for interconnecting two shafts;

A further object is to provide a clutch of reduced dimensions whichfurthermore is virtually free of wear.

We attain these and other objects-by providing a clutch wherein thedrive shaft is coupled by link means to a flange to each side of whichis a rotatable and axially displaceable annular clutch member or ring.Beyond these rings are further rotatable clutch members coupled to thedriven shaft. Mutually engageable frustoconical friction surfaces onthese clutch members permit rotational coupling of them. A small pistonor lever arrangement moves the inside rings out into contact with theouter members'which are ideally in the form of a single housing. Thecentral driven flange is coupled to the two inside clutch members,according to a key feature of the invention, by at least three angularlye'quispaced elongated links. One end of each link is connected viaaball-and'socket joint to the flange and the other end is similarlyconnected to the respective clutch member. These links extendtangentially to an imaginary circle having the clutch rotation axis ascenter and constituting the locus of the pivot axes of the cardanicuniversal joints which are parallel to axis of the clutch, for maximumpower transfer.

According to a further feature of our invention the ball-andsocketjoints comprise a ball head attached either to the flange or the clutchmember, a socket formed in the respective end of the link, and a layerof rubber forming a cushion between the head and the socket. Thesheaming deformation of this rubber serves to stress the joint and pullthe clutch ring back toward the flange when the means for advancing itreleases. The layer is bonded to at least one, preferably both, of theball-and-socket members.

In accordance with a yet further feature of our invention these jointsare made to stress the clutch ring toward the flange even when these twoabut, i.e. whenthe links are in their normal undisplaced position,thereby compensating for loss of elasticity of the rubber or any setwhich it may take durmg use.

As is evident, the links of our invention obviate the need of teethwhich are prone to wear and make-noise. These links operate completelysilently and with virtually no wear, with even no need of lubrication.As long as the elastic limit of the rubber layer is not exceeded, thelinks will last indefinitely.

The particular characteristics of the rubber in the joints' determinesthe amount of pull exerted to return the clutch 7 tion is requiredbetween frustoconical friction members and the flanges rotatablyentrained therewith via the links. Another feature is that the rubber isvery hard to compress thus insuring a minimal amount of play in theclutch.

Another feature of our invention provides that the links be connectedeither with adjacent ends connected to the same side, i.e. either theflange or clutch member. In this manner the rotational force transmittedby these links, regardless of its sense, is carried by half the links intension (pull) and half the links in compression (push).

Should it be more desirable to transmit all the force as either a pushor a pull, a further feature of our invention provides that all the endsof the links turned in the same rotational sense are connected to oneside (i.e. the flange or the frustoconical axially movable clutchmember) and all the ends turned in the other sense are connected to theother of these elements.

The stressing of the ball joints obviates the need for a bulky and oftennoisy return spring. This also allows the overall dimensions of theclutch to be reduced with equaleffective- FIG. 1 is a longitudinalsection through a clutch according to our invention;

FIG. 2 is a section according to line ll-Il of FIG. 1;

FIG. 3 is a view similar to FIG. 2 of an alternative embodiment of ourinvention; and

FIG. 4 is a sectional view of a ball-and-socket joint according to ourinvention, in enlarged scale.

As shown in FIGS. 1 and 2, a drive shaft is adapted to be held in arotatable body or sleeve 1 on which a flange 2 is formed. To either sideof this flange 2 is a respective clutch ring 4 and 5 with afrustoconical clutch surface 10 and II. A two-part housing 12, 13mounted on a sleeve 14 adapted to be coupled to a driven shaft hassimilar frustoconical surfaces which can be engaged by the clutchsurfaceslO and 11.

Small pistons 18 and 19 can be driven against the rings 4 and 5 bypneumatic or hydraulic pressure in their cylinders 16 and 17 which isfed in through a channel 15.

Links 3 couple the flange 2 to the rings 4 and 5. This is shown betterin FIG. 2. Each link 3 has an end 6 attached to the flange 2 and an end6a attached to the ring 4. With this arrangement all the rotationalforce is-transmitted either as a pull or a push in all of the links 3.The axes B of the universal joint which allow cardanic movement, i.e.movement with two degrees of freedom, are parallel to the axis A and ison a com mon circle of radius R in position of the clutch.

FIG. 3 shows an alternative arrangement wherein adjacent ends of atleast one of the links 3 are attached together at one side. In thismanner, regardless of the rotational sense, half of the links transmitthe force in pull and half in push.

In FIG. 4 the ball-and-socket joint at the end 6 of a link 3 is shown indetail. This consists of a ball head 7 with a layer of rubber 8vulcanized to it. A socket 9 formed in the end 6 of the link 3 verytightly receives and hugs this rubber-covered head 7. The fit is sotight that the link 3 resists any angular displacement relative to theball 7 from the position shown in dot-dash lines. In this manner, undernormal conditions the link 3 is stressed to pull the ring 4 or 5 towardthe flange 2. The layer of rubber can be vulcanized in situ to bothmembers of the ball-and-socket joint.

On actuation of the pistons 18 and 19 the two rings 4 move away from theflange 2 and engage the housing halves 12 and 13 thereby entraining thesleeve 14. On release of pneumatic or hydraulic pressure in thesecylinders 16 and 17, the elasticity of the rubber layer 8 quietly andsurely draws the two rings back in toward the flange 2.

The improvement described and illustrated is believed to admit of vmanymodifications within the ability of persons skilled in the art, all suchmodifications being considered within the spirit and scope of theinvention except as limited by the appended claims.

We claim:

1 A clutch comprising:

at least one pair of mutually rotatable about an axis;

at least one body rotatable about said axis and having a flange portion;

means between said body and one of said members for displacing said oneof said members into engagement with the other of said members;

at least one elongated link between said flange portion and said one ofsaid members, said link lyinggenerally skew to said axis and having endsat substantially the same radial distance from said axis; and

respective .ball-and-socket joints connecting one of said ends of. saidlink to said flange portion and the other of said ends to said one ofsaid members..-

2. The clutch defined in claim 1 wherein two such pairs of clutchmembers are provided on opposite axial sides of said engageable clutchmembers body.

1.3. The clutch defined in claim 1 wherein a plurality of such links anda plurality of such ball-and-socket joints are provided in uniformdistribution about said axis.

4. The clutch defined in claim 3 wherein said links extend transverselyto said axis and lie one behind the other in a circular pattern.

5. The clutch defined in claim 4 wherein 'in one sense of rotation ofsaid body, leading ends of said links are connected to said body andtrailing ends of the links are connected to said one of said members,

6. The clutch defined in claim 4 wherein in one sense of rotation ofsaid body the leading end of one link and the trailing end of thepreceding link are connected to said one of said members and thetrailing end of said one link and the leading end of the following linkare connected to said body.

7. The clutch defined in claim 1 wherein each of said ball jointscomprises a ball head, a socket receiving said head, and a layer ofelastic material between said head and said socket.

8. The clutch defined in claim 7 wherein said ends of said link areformed with such sockets.

9. The clutch defined in claim 7 wherein said layer of elastic materialconsists of rubber and is vulcanized on said head 10. The clutch definedin claim 9 wherein each of said ball joints is stressed to draw said oneclutch member toward said body.

